From cc004f5a86f4c3ae427faa46719127408685d532 Mon Sep 17 00:00:00 2001
From: Drashna Jaelre <drashna@live.com>
Date: Sun, 9 May 2021 23:21:09 -0700
Subject: [PATCH] Make Swap Hands use PROGMEM (#12284)

This converts the array that the Swap Hands feature uses to use PROGMEM,
and to read from that array, as such. Since this array never changes at
runtime, there is no reason to keep it in memory. Especially for AVR
boards, as memory is a precious resource.
---
 docs/feature_swap_hands.md    | 2 +-
 docs/ja/feature_swap_hands.md | 2 +-
 tmk_core/common/action.c      | 3 ++-
 tmk_core/common/action.h      | 2 +-
 4 files changed, 5 insertions(+), 4 deletions(-)

diff --git a/docs/feature_swap_hands.md b/docs/feature_swap_hands.md
index 009477d20334..cbc574b6b866 100644
--- a/docs/feature_swap_hands.md
+++ b/docs/feature_swap_hands.md
@@ -7,7 +7,7 @@ The swap-hands action allows support for one-handed typing without requiring a s
 The configuration table is a simple 2-dimensional array to map from column/row to new column/row. Example `hand_swap_config` for Planck:
 
 ```C
-const keypos_t hand_swap_config[MATRIX_ROWS][MATRIX_COLS] = {
+const keypos_t PROGMEM hand_swap_config[MATRIX_ROWS][MATRIX_COLS] = {
   {{11, 0}, {10, 0}, {9, 0}, {8, 0}, {7, 0}, {6, 0}, {5, 0}, {4, 0}, {3, 0}, {2, 0}, {1, 0}, {0, 0}},
   {{11, 1}, {10, 1}, {9, 1}, {8, 1}, {7, 1}, {6, 1}, {5, 1}, {4, 1}, {3, 1}, {2, 1}, {1, 1}, {0, 1}},
   {{11, 2}, {10, 2}, {9, 2}, {8, 2}, {7, 2}, {6, 2}, {5, 2}, {4, 2}, {3, 2}, {2, 2}, {1, 2}, {0, 2}},
diff --git a/docs/ja/feature_swap_hands.md b/docs/ja/feature_swap_hands.md
index 3150801c5542..5164584e8a47 100644
--- a/docs/ja/feature_swap_hands.md
+++ b/docs/ja/feature_swap_hands.md
@@ -12,7 +12,7 @@
 設定テーブルは列/行から新しい列/行にマップするための単純な2次元配列です。Planck の `hand_swap_config` の例:
 
 ```C
-const keypos_t hand_swap_config[MATRIX_ROWS][MATRIX_COLS] = {
+const keypos_t PROGMEM hand_swap_config[MATRIX_ROWS][MATRIX_COLS] = {
   {{11, 0}, {10, 0}, {9, 0}, {8, 0}, {7, 0}, {6, 0}, {5, 0}, {4, 0}, {3, 0}, {2, 0}, {1, 0}, {0, 0}},
   {{11, 1}, {10, 1}, {9, 1}, {8, 1}, {7, 1}, {6, 1}, {5, 1}, {4, 1}, {3, 1}, {2, 1}, {1, 1}, {0, 1}},
   {{11, 2}, {10, 2}, {9, 2}, {8, 2}, {7, 2}, {6, 2}, {5, 2}, {4, 2}, {3, 2}, {2, 2}, {1, 2}, {0, 2}},
diff --git a/tmk_core/common/action.c b/tmk_core/common/action.c
index aae5cbfa5feb..f41665b06cbb 100644
--- a/tmk_core/common/action.c
+++ b/tmk_core/common/action.c
@@ -133,7 +133,8 @@ void process_hand_swap(keyevent_t *event) {
     bool             do_swap = event->pressed ? swap_hands : swap_state[pos.row] & (col_bit);
 
     if (do_swap) {
-        event->key = hand_swap_config[pos.row][pos.col];
+        event->key.row = pgm_read_byte(&hand_swap_config[pos.row][pos.col].row);
+        event->key.col = pgm_read_byte(&hand_swap_config[pos.row][pos.col].col);
         swap_state[pos.row] |= col_bit;
     } else {
         swap_state[pos.row] &= ~(col_bit);
diff --git a/tmk_core/common/action.h b/tmk_core/common/action.h
index 9a991de1c2ba..6c84561785c3 100644
--- a/tmk_core/common/action.h
+++ b/tmk_core/common/action.h
@@ -78,7 +78,7 @@ extern bool disable_action_cache;
 /* Code for handling one-handed key modifiers. */
 #ifdef SWAP_HANDS_ENABLE
 extern bool           swap_hands;
-extern const keypos_t hand_swap_config[MATRIX_ROWS][MATRIX_COLS];
+extern const keypos_t PROGMEM hand_swap_config[MATRIX_ROWS][MATRIX_COLS];
 #    if (MATRIX_COLS <= 8)
 typedef uint8_t swap_state_row_t;
 #    elif (MATRIX_COLS <= 16)